a) for 25 therms
cost = $.6686(25)) = $16.72
b) cost = 16.72 + (45-25)(.8587
= $33.89
c) cost = (x-25)(.8587) + 16.72 , for x > 25
or = .6686x , for 0 < x ≤ 25
A utility company has the following rate schedule for natural gas usage in a city's district: Monthly service charge of $8.80; Per therm service charge: 1st 25 therms: $0.6686/therm; Over 25 therms: $0.85870
(a) What is the charge for usaging 25 therms in one month?
(b) What is the charge for using 45 therms in one month?
(c) Construct a fraction that gives the monthly charge c for x therms of gas.
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